Good question. I have an Aquarite and keep the CYA at around 60+. I have found that I have to keep my FC up in the 4 to 5 range in order to prevent algae growth, especially when it rains and stuff gets washed into the pool. If I let it drop to the recommended 1 to 3, the pool becomes easily "upset" by extra bather load or bioload from stuff blowing in. Then I have to shock with bleach or superchlorinate to prevent or beat back cloudiness.

Keeping the FC at 4 or 5 isn't an issue (I run at about 35% for about 12 hours total a day into a 28k gallon IG pool), it is just an interesting question about whether the 1 to 3 recommendation is sufficient.